I haven't looked to close at this yet but will stick my neck out and
say yes I believe it will work just fine. At 9000 rpm on a pp with a
T bar and 2 magnets your resolution would be 300% better than what
the gear slop alone could give you. I haven't counted the gearing but
let's say it's 50:1, even a 30 rpm shaft with 2 magnets on a T bar
will give you better than 1/4 degree resolution. You only need 1
degree.... Jeff in conversation calculated out my new retrofit for
the pst motor at 1/10 of a degree or something like that. Suffice to
say it's got plenty of pulses :) (15,500 per antenna revolution I
think was the number, you can do the math)
Several have sent pics of motors, will look at this when I get some
time. Don't see it as being a problem though and you would increase
the reliability of the unit by a gazillion % with a hermetically
sealed switch. Obviously must have the rt20/21 controllers for
flexibility of setting up but this seems to be the new standard for
making all this stuff work.
Scott
N1CX
At 07:22 AM 4/3/2014, john@kk9a.com wrote:
A reed switch works great on a prop pitch motor, where the motor is
spinning 7000-9000 RPM. The shaft that the TIC pot is connected to turns
much slower so I am not sure how accurate the indicator would be. TIC
used to use Bourns potentiometers which were somewhat sealed. They were
not perfect, but I have had good results with these. I do not know if the
Vishay unit has any shaft seal. One big problem with the TIC motors is
that water can leak around the gear shaft and into the pot, which has the
shaft pointing up. It would be nice if the motor were installed upside
down. While in Illinois I had many pot failures when it got below freezing
and any moisture inside froze. I installed motor heaters which helped a
lot. A pot that is highly moisture resistant would be an easy solution, if
such a thing exists. I spent an hour or so yesterday searching for
replacement potentiomers and so far I have not found a better solution.
John KK9A
To: towertalk@contesting.com
Subject: Re: [TowerTalk] TIC Potentiomenter
From: Fred Sanborn <cc-6569@comcast.net>
Date: Wed, 02 Apr 2014 18:59:10 -0500
John,
I agree the Vishay 10T pot does not seem to be a good solution. I "worked"
the pot back and forth more today and it never came back enough to be able
to use the RT-21 without the "no motion" error message again. We did have
a sever winter here in N. IL with a good amount of precipitation. However,
I just did a pot replacement and put the rotor back in service September
so I am very disappointed.
I am serious when I put the question out there to the TowerTalk community.
Has anyone considered or implemented a redesign of the TIC ring rotor
direction indication method to get away from the dreaded unreliable pot?
TNX es 73, Fred KG9X
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